The Japanese patent No. 2535964, for example, discloses a cutting tool device of a machine tool having a fraise cutter fixed to the tip of a rotating shaft and provided with a suction cover covering the surrounding portions, except for the tip face, of the cutter.
This cutting tool device moves in a direction transverse to the rotating shaft during use. The fraise cutter machines a work surface of a workpiece in a plane during its movement. On the other hand, air inside the suction cover is drawn by an air suction device arranged separately and is eliminated in another place. Because of this elimination, an air flow generated around the fraise cutter acts to continuously discharge to the other place chips produced by machining with the fraise cutter.
In the above machine tool, plural kinds of cutting tool devices, in each of which the longitudinal distance between the tip face of the fraise cutter and the tip face of the suction cover is suitably changed, are usually prepared for various machining steps, such as a roughing step and a finishing step, in relation to an uneven size of the work surface and the amount of material to be cut with each pass of a cutting element. These cutting tool devices are used so that exchanging of the devices may be carried out for each machining step to the end of the cutting work.
The above-described conventional cutting tool device is uneconomical in preparing different cutting tool devices for each machining step of the work. Besides, these devices need to be exchanged during the machining, thereby taking more time, as well as having a disadvantage in keeping cutting accuracy. An object of this invention, therefore, is to propose a cutting tool device for a machine tool that can overcome the above problems. 